Primary conning teacher



April 27, 1954 W. E. STEPHENS ET AL PRIMARY CONN ING TEACHER Filed Nov. 20, 1943 e sneets-sheet 1 SMQZM April 27, 1954 w. E. STEPHENS ET A1. 2,676,419

PRIMARY CONNING TEACHER Filed Nov. 20, 1945 6 Sheets-Sheet 2 Pl/lliam E Stephens ma# 6kg/lord [Zhi-@Well April 27, 1954 w. E. STEPHENS ET A1.

PRIMARY coNNING TEACHER 6 Sheets-Sheet 3 Filed Nov. 20, 1943 SUBMARINE l AHIDSHIP LEFT RUDDER CONTROL William E Sfepens 11d @gr/lord A? Harnufe!! April 27, 1954 w. E. STEPHENS ET AL 2,676,439

PRIMARY coNNING TEACHER Filed NOV. 20, 1943 6 Sheets-Sheet 4 vbz ffy 4 2/ /4 WZ /9 /7 "9,1 N R W-,

gri/UWM M-s mam E Stqven ff Gay/lord @Harnwell @M gg@ g @www April l27, 1954 w. E. STEPHENS ET AL 2,676,419

PRIMARY CONNING TEACHER Filed Nov. 20, 1943 6 Sheets-Sheet 5 Wlliam E Sephem wf qylord Rb'm'uzvell awww@ April 27, 1954 w. E. STEPHENS ET AL PRIMARY CONNING TEACHER 6 Sheets-Sheet 6 Filed Nov. 20, 1943 MNE-.PUNK I Willi w" G25/l0 Patented Apr. 27, 1954 2,676,419 PRIMARY CONNING TEACHER William E. Stephens, Philadelphia,

P. Harnwell, La

lord the United States of lua., and Gay- .lolla, Calif., assignors to America as represented by the Secretary of the Navy Application November 20, 1943, Serial No. 511,130

9 Claims.

' This invention relates to a training device and one which, in particular, is adapted to portray in two dimensions the projected relative motion between two moving objects."

One very useful application of the device which will be described in detail is a machine adapted this is only one of many uses, as the same general arrangement can be used to study the velocity relationships, as projected on a plane, between anyk two objects moving with respect to each other. Thus whether the Objects be ships, aircraft or any other moving bodies, the device may be used. It may be utilized in such iields as nre control, attack procedure, radio and sound detection, etc.

For training in anti-submarine attack procedures, the device consists primarily or two transu lucent screens, onto the back of each of which is projected a moving light spot representing one of the vessels involved in the attack. These screens are mounted in opposite ends of a rectangular box, and are designated the Destroyer position and the Submarine position. Controls are provided at each position by means of which the operators may simulate the movements of their respective ships, as represented by the movement of the light spot on the screens. Thus, by the use of the controls, the student, as though he were aboard an anti-submarine vessel, such as a destroyer, imagines his position to be at the center of the screen and endeavors to maneuver his ship, by means of the controls, into a proper1 position for attacking the subrnarine, The instructor, stationed at the opposite position, conversely, attempts to maneuver his submarine, by means of his controls, to avoid such a successful attack.

The invention is principally intended to provide preliminary practice for students in dealing with the relative movements of the ships involved in an anti-submarine attack by a surface craft equipped with standard echo-ranging equipment, although, it may, with minor changes, be

approximately obtain similar information from a vgood, sound operator..v On

the panel before him, the student is provided with engine and rudder controls with which he can change the speed and course of his ship and a course dial which indicates the direction of the ship. Delays are incorporated into the rudder control to simulate the lag in response of the ship to the helm; the rate of turning is also a function of the ships speed. The turning rates may be selected so as to be appropriate for an average ship. of the class which the instrument is intended to represent. The shipsV speed is changed Without time lag.

At the opposite end of the machine is a second control station. in the normal use, as an elementary cunning trainer, this position is occupied by an instructor who faces the screen and imagines his ship (the submarine) to be at the center of the screen on the course indicated by the course dial. The light spot then portrays the movement of the destroyer with respect to the submarine. The screen is calibrated for bearings but not for ranges. The light spot representing the surface ship appears continuously on the submarine screen. Controls for changing the speed and course of the submarine are provided, and appropriate delays and turning rates are included.

At the beginning of each run the instructor sets the light spot according to the requirements of the exercise, starts the problem by operating a switch and thereafter provides the conning student with such additional information as the diiiiculty of the exercise demands. At the conn clusion of the run, the instructor evaluates the attack and scores the problem.

At the very beginning of a studcnts instruction, the problems would be very simple. For example, the student would be given the speed Commander who employs all of the evasive tricks at his command to avoid destruction.

Various criteria of judgment may be applied in evaluating an attack.

ship so as to be on the correct bearing at the instant of Fire When this method is used, the attacking ship :is held steady on its course after the instant of Fira the submarine continues freely on its course and the motion of the light spot is stopped ataipredetermined range the positions vof the charges.

by means of a switch. The student is then held responsible only for the deviation of his course from the final bearing of the spot and is scored accordingly.

Alternatively, the student may be held responsible for the time of Fire as well as for the correct ships course and he operates the firing button according to his best judgment. The scoring of the problem is then made to depend on the position of the submarine with respect to the charge at the instant of explosion. The explosion occurs at one of two iixed times after the button is pressed, depending on which way the student has operated a switch for specifying the type of attack to be used (depth charge or forward thrower). When ready to lire, the student pushes a firing switch which does three things: (l) it stops the motion of the destroyer and lights a signal lamp behind the screen to indicate the release time; (2) it starts an interval timer which, when the predetermined time has elapsed, extinguishes the signal lamp behind the screen and thus indicates the time oi explosion; but (B) it .permits vthe submarine to continue on its course. Upon the explosionof the charges (indicated by the extinction of the signal light) the problemis stopped and the position of the submarine light spot measured with respect to In locating the latter positions, if Vthe attack has been made with depth charges, due account must be taken of the dead time and the distance from the sound projector tothe stern of the ship. If the attack is with a forward-thrown projectile, it is necessary to take into account the speed of the ship and the distance of the projector-head to the forward-throwing racks.

In the drawings:

'Figure 1 is a side elevation of the invention, showing the switch panel.

Figure 2 is an en'd elevation of the invention, showing the Destroyer position.

Figure 3 is the opposite end elevation, showing Vthe Submarine position.

Figure 4 is a mechanical schematic drawing of the optical system.

Figure 5 is aside view of the assembly of Fig. 4 with the light sources omitted.

Figure 6 is a side elevation of the destroyer steering motor and related cam system.

Figure 7 is a sectional view along the line l-i of Fig. 6 but with the potentiometer winding removed.

Figure 8 is a schematic drawing of the electrical circuits.

GENERAL DESCRIPTION A side view of the invention is shown in Fig. 1. As is seen, the device is enclosed in a box having a switch panel l on one of its sides, adjacent to one of the end panels. The two'end panels 2, 3 form a Destroyer and a Submarine position, respectively.

The Destroyer position or end panel 2 is shown in Fig. 2. It comprises a translucent screen A mounted in an opening in the panel, which screen is marked off into radial lines with a 360 radial scale at its diameter and circular divisions radiating from its Center to indicate ranges or distances. At one corner of the panel 2 is a destroyer is rotatable and provided with a pointer to indicate the simulated course of the destroyer on a fixed 360 radial scale at the circumference of the dial.

On the same panel is mounted the destroyer similar to switch'S-'B and rudder control switch S-B which is operated by turning the knob. Switch S-B has three positions, Left, Amidships and Right, to indicate the direction in which the destroyer is steered, as shown in Fig. 2. By pulling or pushing this same knob into or out of the panel, the destroyer rudder speed switch S-l2 is operated. Two signal lamps L-i and L- are mounted adjacent switch S-8 to indicate left and right rudder by means of their red and green colors, respectively. Adjacent switch S-S is a destroyer speed switch S-B for controlling the simulated speed of the destroyer. A depth charge release switch S-ll is also included on panel 2 together with switch S40 for choosing the kind of an attack to be made.

The opposite end panel 3 of the box, or the Submarine position, is shown in Fig. 3. It contains a screen 6, similar to screen il but has no range or distance designations, as the Submarine O-iiicer ordinarily would only be provided with bearings and not ranges. The panel also contains a submarine course dial 1, similar to dial 5, which indicates the course of the submarine. Likewise, there is a submarine rudder control switch S-S having the same positions to indicate the direction of turning of the simulated submarine. Two signal lamps L-5 (red) and L- (green) indicate the vposition o switch S-S. Switch S-1, corresponding to switch 5 6, controls the speed of the submarine.

OPTICAL SYSTEM The optical system used in the invention to reflect the light spots on the screens is one involving a differential arrangement, so that both horizontal and vertical movements (on the screens) are obtained. Since the screens are mounted back to'back and the spots indicate relative positions of the two vessels, the spots are reiected on the two screens at opposite angles. Although there are many methods oi obtaining this desired result, a convenient one is illustrated in the schematic diagrams of Figs. 4 and 5.

A pair of mirrors 8, 9 is mounted midway between the translucent screens A, G (shown only in Fig. 4) to reflect spots of light produced by the fixed individual light sources I r-l and L-2 onto the screens. In'order that the spots are given proper motion, the mirrors 8, '9 are rotatably mounted on pins I6 in a yoke hi. The yoke, in turn, is rotated by a motor W-I, which may conveniently be a watt-hour meter, through shaft l2 'and reduction gear box I3 to give vertical (north-south) motion to the spot, as reflected on the screens 4, 6. The horizontal (east-west) 'component of the inotion is supplied by the rotation of a similar motor W-2, which drives pinion lli, through shaft l5 and gear reduction box l5. Gear i4 is positioned to mesh with rack l1 formed on shaft I8, which shaft has a nat head i9 at its end positioned between mirrors 8, 9. The shaft operates like a piston and its head slidably engages two arms 20, 2l, one of which is attached to the back of each mirror. A small spring 22 is mounted between the two mirrors, as shown in Fig. 4, to re-position the mirrors as shaft I8 moves outwardly from them. Thus, it is seen that the mirrors rotate about the axis of pins ri, as shaft I8 moves` longitudinally toward and away from the arms 2G, 2l attached to the backs of the mirrors. In this manner, rotation of watt-hour meter W-2 is enabled to produce the horizontal (east-west) component of the movement of the spots on the screens 4, 6.

From the-arrangementjust described it ispo'ssible to cause the light spots'to move on the screens in any desired direction and amo-unt, as controlled by the rotation of watt-hour meters W-l and W-Z. Since, in the invention, the center of each screen is the reference point and the light spot indicates the relative position of the opposing vessel, it is clear that the position of the spot with respect to (and itsmovements about) the center of the screen represent relative motion between the two vessels. It is therefore necessary to supply to watt-hour meter W-l voltages proportional to the difference between the vertical (north-south) components ofthe velocities. of the simulated destroyer and submarine; and to watthour meter W-Z, voltages proportional to thedifference between the horizontal (east-west).V .components of the samevelocities,Theseucomponents obviously changeaccording to thedirection and speed of the two vessels. Y

Figures 4 and 5 also illustrate the intermittent character of the light reiiected to the destroyer screen il. In conventional echo-rangingprocedure, the destroyer Conning Ofiicerreceives information of the bearing and range of the submarine only at intervals. Thus, there is provided a shutter motor IVI-3 which, through shaft 23 (also shown in Fig. 8) drives a circular shutter 2li formed with sector-shaped slots, as shown in Fig. 5. This shutter is mounted directly in front of mirror 3 and between it and the destroyer screen 4) so that the light spot is reiiected onto the screen four times during each revolution of the shutter 24. This shutter arrangement is provided only for the destroyer screen, since in practice, the submarine will have continuous information about the bearing of generally provided with echo-ranging, gear.

In Figs. 6 and 7 is shown a schematic arrangement of the destroyer steering motor M-l and a means for obtaining electrical values proportional to the component velocities. The steering motor -l is connected directly to the destroyer course dial 5 (mounted in panel 2) by means of shaft 25. Two cams 26, 21 are keyed to shaft 25 by means of set screws 28, and one of the cams is rotated through an angle of 90 with respect to the other, such that one camwill produce motion proportional to the sine and the other to the cosine of the course angle as determined by the destroyer course dial 5. Thus, for any given course angle, the cams enable the measurement of the north-south and east-west component of any velocity at such angle.

A frame 29 nXed with respect to motor M-l carries two slidable rods 30, 3l which carry small rollers 32 in their lower ends. The rollers are forced into contact with the cams 2E, 27 by means or springs 33 and thus, as the cams rotate, the rods are forced up and down as the motor ll/I-l and cams 25, 27 rotate. The curve of the cams (as shown in Fig. 7) is such that the linear motion of the rods 3i), 3l and rollers 32 are proportional to the sine and cosine of the angle through which the cams rotate, as measured from a reference position.

Fixedly mounted on each of the sliding rods is a contact which, together with the winding fixedly mounted in frame 29, forms potentiometer P-i. The potentiometer is center-tapped as shown in Fig. 8, and thus the positions of the contacts enable the application of voltages proportional to the sine and cosine of the destroyer course angle to watt-hour meters lf .,-l and W2.

A similar arrangement-,ds made-ruse of to Lob..-

the destroyer, as it is listening, rather than ELECTRICAL CIRCUIT AGeneral The electrical system which is used in conjunction with the invention is shown schematically in Fig. 8. It is to be understood that the particular arrangement set forth herein is illustrative only and that other methods will be known to those skilled in the art. However, Fig. 8 shows a circuit which has performed satisfactorily and will therefore be described in detail.

The method of designation for relays should rst be explained. Many of the relays have a separated on the drawing. Each has an actuating coil which has an adjacent designation, as

which indicates that it is relay F-4 and is provided with 8 contacts. At other places on the diagram where the contacts are illustrated, the designation F- will appear, together with the particular contact number involved. Normally open contacts are designated by a small open triangular contact, and normally closed contacts by a solid triangular contact.

The whole electrical circuit may be supplied from a 11G-Volt, E50-cycle line controlled by power switch S-l and is found to require approximately three amperes, although five-ampere fuses may be used. Light sources L-l and L2 are supplied from the line through transformer T-3, when switches S-l and S-2 (both of which are mounted on the switch panel l shown in Fig. l) are closed.

The mirrors 8, 9, described above, are driven by the watt-hour meters W-l and W-2. current coils of the watt-hour meters are provided with lixed values of current from the line through current transformer T-2. The voltage coil of watt-hour meter W-I is energized by a variable voltage supplied from potentiometers P-l and P-2 and which, at any given instant, is proportional to the north-south component of the relative motion of the destroyer and submarine, as has been described. Similarly, the voltage on watt-hour meter W2 is proportional to the east-west component of the,` relative motion. The resistors R-M and R-l5 in series with the current coils are used during assembly to make final adjustment of the rates at which the spots travel across the screens.

For the purpose of quickly resetting the position of the light spots on the screen, the voltage coils of watt-hour meters W-l and W-Z are connected to double-throw spot reset switches and S-5 (which are also mounted on the switch panel l shown in Fig. l), when problem switch S-3 is in the Oi position, As isobvious,

alava-,4119

operation of the reset 'switchesconn'ectstlie 110- volt supply tothe Voltage 'coils'to provide rapid rotation of the watt-hourmeters in a direction determined bythe throw of the switch (Up or Down for swich S-'4; 'Right or Left for switch S-). The reset switches 'are automatically disconnected whenproblem switch S-3 -is in the On position.

During the'normal useof the instrument, the voltages applied to thewatt-hour meters are derived from transformer T-i. The Aprimary of transformer T-I is'energized only when problem switch S3 is in the On position. Two tapped secondary windings provide voltages proportional to the destroyer rand submarinespeeds, the particular voltages used being selected by one section of eachof the speed switchesS-S and S-1. mounted on the Destroyer and Submarine panels, respectively. These voltages are applied across the resistance potentiometers P-l and P-Z which are mounted on the steering motors M-I and'M-Z (see Figs. 6 and 1). )Each of the potentiometers is center-tapped and is provided with two sliding contacts. The position of the contacts with respect to the center cams mounted on the motor shaft `as heretofore described. The cams are so shaped and oriented on the shaft that when the motor -is turned to a giventrue course as indicated. by the course dial, the voltage between the center tap and one v of the contacts is proportional to the east-west component of the ships motion on that course at the selected speed, while the voltage between the center tap and the other contact is proportional to the north-south component or" the motion. The center taps of the potentiometers P--l and P-2 are connected together, as shown in Fig. 8, and are the reference point from which the voltage components are measured. The sliders of the potentiometers connect to therespectivevoltage coils of watt-hour meters W-2 and W-l. The secondaries of transformer T-l are so poled that the net voltage applied to watt-hour meter W-l is the difference of the voltages obtained between the center tap and the corresponding sliders on the two motors, to give a net voltage which is proportional to the relative north-south motion of the destroyer and the submarine. Similarly, the watt-hour meter W-Z yis energized by a voltage proportional to the relative eastwest motion. Since the watt-hour meters are supplied with constant current, their rate of turning is proportional to the applied voltage; hence the movements of the mirrors, and the motions of the light spots on the screens, correspond to the course and speed settings at the destroyer and the submarine positions.

Destroyer steering 'motor circuit The destroyer steering motor M-l is a reversible, single-phase, shaded-pole motor, 4connected to rotate the cams 26, 21 as described. VSpeed changes are eiiected by inserting resistance in series with the shading coil windings. The rate of change of course (rate of turning of the motor M-i and cams 26, 21) is a function of both the degree of rudder and the ships speed. The direction and rate of turning are both controlled by rudder control switch S-8, mounted onthe Destroyer panel 2. Externallly, switch S-8 (see Fig. 2) has threepositionsLeft, Amdships 'and Right, and is composed of two rotating contact'arms, one for introducing 'xed amounts of resistance into the delay circuit which 'prevents :immediate rotation lof 'steering yn'oto'r IVI-"I upon operation tap is controlled by two oflswitch S-B l(to simulate'the delay occurring before actual turning of a ship, after the rudder is swung), and the other for operating a set of relays to be described.

Additionally, there is a rudder speed switch S-'|2, provided with Full and Slow positions as shown in Fig. 8. This is to simulate fast or slow turning of an actual ship. For convenience, this switch may be mounted on the same shaft as switch S-B and operated by simply moving the shaft in or out with'respect tothe front panel as shown in Fig. 2.

The time-delay circuit for the destroyer steering motor is composed of condenser C-l and tube V-I, the latter being provided with a selfbiasingresistor R-IG anda by-pass condenser C4. This is'supplemented by a condenser C-i and `a rectier V-li, which circuit provides charging current for the destroyer steering time-delay circuit, as well as rall other time-delay'circuits in the invention.

In order to understand the operation of switch S-, assume that it is in the Amidships position (with switch S-l2 lin the Full position), and rotated to the Leit position. Motor i -i will not start to rotate (or the course change) until after an interval established by the `time-delay circuit. The rotary switch arm of switch S-B momentarily touches an intermediate contact in traveling from the Amidships to the Leit positions thereby charging condenser C-l, connected between the grid and cathode of time-delay tube V-i, from the voltage output of rectifier V-li. The grid of tube V-I is made suniciently negative by the'charge on condenser C-l so the plate current ci the tube is practically zero. As soon as the switch S- isin the Left position, the condenser C-l starts to discharge through resistor R-. ri`hus,'the grid gradually becomes less negative and the `plate current rises until two-contact relay F-l operates. The operation of this relay completes the circuit to eight-contact relay F-'l and lights the red signal lamp L-3 mounted on'the Destroyer panel 2. The operation of re- 'lay F-ll causes the following actions to occur:

(a) Contacts l and 2 of relay F-, together with contacts 3 and 4 of eight-contact relay F- and contacts l and 2 of two-contact relay F-2, form a locking circuit to hold relay F-f-l when relay F-I releases.

(b) Contacts 3 and A of relay F-4 open the circuit to relay F-5 to prevent both relays F-fi and F-E from locking simultaneously if the switch S-8 is thrown from the Leit to the Right positions without a stop in the Amidships position.

(c) Contacts 5 and 6'oi relay F-li short-circuit one half of the shaded-pole winding of motor M-l.

(d) Contacts 1 and of relay F-ll connect one of the resistors, R-I, R-Z or R-3, in series with the other half of the shaded-pole winding. -As can'be seen from Fig. 8, the particular resistor used depends on the setting of speed switch S-E.

The result is that motor M-l turns to the left at a rate determined by the setting of switch S-B and will continue to turn in that direction until some change is made in the control switches. If switch S-B is turned to a new speed position, the motor lVI-l immediately starts to turn at the 'new 'rate determined by the value of the particular resistor (R-l, R-2 or R-B) inserted in the circuit. It should be noted, however', that a delay circuit similar to that described above could also be used vin connection with switch position could be utilized.

When the rudder control switch S-B is returned to the Amidships position, relay F-I irnmediately releases, but relay F-ll remains operated through its locking circuit. Condenser C-i is again charged as the switch arm on switch S-S moves over the contact intermediate the Left and Amidships positions and tube V-i is rendered non-conducting. Condenser C-l now discharges through resistor R-S and after an interval determined by the value of R-, the plate current in tube V- is suincient to operate two-contact relay F-2.

switch S-B is again moved from the Amidships position.

If switch S-S is moved to the Right position similar operation occurs. lRelay F-Z immediately releases, and two-contact relay F-S operates after its pre-determined delay (similar to relay F-I). The operation of relay F-3 closes the circuit to relay F-, which locks and lights the green signal lamp L4 (also mounted on the Destroyer panel 2). The proper shaded-pole winding is now short-circuited to make the motor M-I turn to the right. When switch S-s is returned to the Amidships position, relay R-Z operates, thereby extinguishing lamp L-d and releasing relay F-s which stops the motor.

Submarine steering motor circuit The submarine steering motor M-2 is operated in a manner similar to the destroyer steering motor M-I and reference is made to the description above for the specific method of operation of both. The motor M-2 is controlled by the submarine rudder control switch S-9 (which operates like switch S-3), mounted on the Submarine panel 3 shown in Fig. 3. However, only Full rudder is provided and thus no submarine rudder speed switch is provided (corresponding to switch S-i 2), although this might easily be included if desired. The submarine time-delay circuit comprises tube V-2, condensers 5, C-Z and R-ll (which correspond to and operate as did tubes V-i, C-il, C-l and R-B respectively). Resistors R-Iii and R-I l, which correspond to resistors R-i and R-9 in the destroyer circuit, are chosen toprovide the proper delays in going into and coming out of a turn. Relays F- and F-l (corresponding to relays F-3 and F-5) operate when switch S-Q is switched to the Right position, while in the Left position relays F-i and F-S (corresponding to relays F-l and F-li) areeiective. The rate of turning is determined by resistor R-5, R-G or R- fl (corresponding to resistor R-l, R-2 or R-3, respectively) connected to the submarine speed switch S-'l (corresponding to destroyer speed switch S-(i) mounted on the Submarine panel 3.

vBarrage release circuit panel as shown in Fig. 2. When ,Switch Srl l is 10 momentarily closed, eleven-contact relay F-II operates and lights signal lamp L-7. Lamp L-1 is positioned at the edge of and behind the destroyer screen d, so that it throws a diiuse light onto the screen while it is burning. Additionally, when relay F-i I operates, the following sequence of events takes place:

(a) Contacts 2 and 3 on relay F-l i open the 11G-volt supply circuit to the destroyer steering motor M-l so that the destroyer motion cannot change in course during the time interval between the release and the theoretical explosion of the charge (while lamp L-l is burning).

(b) Relay F-Ii locks through its contacts l and 2, in series with the normally closed contacts i and 2 of two-contact relay F43.

(c) Contacts t and 5 of relay F-ll remove the charging voltage from condenser C-3, starts to discharge through resistor R-I 2 or R-I 3, depending upon the setting of switch S-I, to be described. r

(d) Contacts 6, 7, S and 9, it, Il of relay F-H disconnect the sliders on potentiometer P-i on the destroyer steering motor M-i from the watthour meters W-i and W-2, and connect one terminal of each watt-hour Two positions, Throw Forward and Drop Astern, are provided on switch S-lii to determine the time interval for the discharge of condenser C-S. Thus when switch S-i 9 is in the Throw Forward position, condenser C-3 discharges through resistor R-iz in an interval somewhat shorter" than when it is in the Drop Astern position, and the condenser discharges through R-IB.

At the end of this interval, two-contact relay F-iZ operates and closes the circuit to two-contact relay F-i3. When relay F-IB operates, it

circuits to normal.

OPERATION Before the device is operated, the circuits should rst be connected to a 11G-volt, 60-cycle supply, through contacts which may conveniently connected, power the machine may be set into actual operation by placing the problem switch S-3 on the switch panel in the On position. y

The spot, as reflected on the two screens, 4, 6 will now begin to move with direction and speed determined by the destroyer and submarine speed settings and by the courses indicated ontheA Boththe student and thi'nJ' course dials 5, l?. i structor are now free to maneuver their respec- 1l tive vessels. It should also be notedthat while the problem switch S-S is inthe On position, the

Operation from the destroyer position The destroyer is assumed to be at the center of the destroyer coordinate screen l and the center of the light spot indicates the true bearing of the submarine in degrees and its range in yards as measured from the sound projector head. The light spot will appear on the screen at intervals (3.75 seconds, for the values given in Fig. 8) determined by the rotation of shutter motor M-3 and the number of slots in shutter 2li. The precisely equal time intervals between successive appearances of the light spot may be used by the student in calculating range rate For example, if the radial advance of the light spot is 30 yards per flash, the ships are approaching at This is a range rate of 14.4 knots.

The true course of the destroyer is indicated on the destroyer course dial 5. Changes in course are eiiected withthe rudder controlswitch S-B which providesfor changes in the degree of rudder as well as for specifying the direction'of the rudder. Rudder is applied by rotating` the switch to the Right or Left position; and is taken ofi by restoring it to the Amidships position. When the switch knob used in operating the switch S`8 is pulled or pushed frompor towards the Destroyer panel, Full or Slow' rudder turning speeds may be obtained. When the Right or Left rudder is put on, the course-does not start to change until a period of 12 seconds has elapsed; when the rudder is restored to the Amidships position there is a delay of e seconds before -the course becomes steady (for the various circuit values given). The red or green signal lamp L'-3 -or 4, is lighted whenever the course is changing to the left or right, respectively. The delays are independent of the Full-Slow setting of the switch. After the course has started to change, however, a change in either direction between Full and Slow positions may be made without delay; but if the rudder switch S-B is changed from the Right or Left position to the opposite position without stopping at Amidships, the course continues to change in the original direction for 12 seconds before reversing, to simulate the actual operation of a destroyer (as determined by the delay circuit described above).

The speed of theV destroyer is determined by the setting of the speed switch S-S on the Destroyer panel 2. With the values given in Fig. 8, speeds of 0, 10, 15 and 20 knots are obtainable. No delay is encountered inA going from one speed to another. The rate at which the course changes when Full rudder is applied is a function of the destroyer speed (as is seen in Fig. 8), while the turning rate-for Slow rudder is the same vfor all speeds.

Operation from the submarine position The submarine is assumed to be xed at the center of the submarine coordinate screen and the center of the light spot indicates the true bearing of the destroyer. The light appears continuously on the submarine screen, as no shutter arrangement is provided. The true course of the submarine is indicated on the submarine course dial l mounted on the Submarinepanel 3 (see Fig. 3). The operation of the'rudder control switch S-Q is similar to that described previously for the rudder control switch-S-S for the destroyer. The delay in initiating a turn vis lseconds, while the delay for returning tonormal course after turning is 5 secondsifor the, valuesgiven' inFig. 8). Only Full rudder is provided vfor thesubmarine as has been described. One of the signal lamps L- or L- on the Submarine panel 3 `is lighted whenever the course is changing. Speeds of 0, 3, 6 and 9 knots are provided, with the values given in Fig. 8.

Scoring the problem Several alternative methods may be utilized in scoring the attack procedure adoptedby the student. If no barrage is released by the operation of the depth charge release switch S-l I, the motion of the light spotlmay be stopped at the specified time simplyl by placing the problem switch S-3'in its Oiposition. This will noteffect any course changes thatv are in progress and steady courses can be obtained by restoring the rudder control switches Svp-8 and S-9, to their Amidships positions.

When it is desired-to'vsimulate the release of a barrage, thestudent sets the switch S-I 0 to either the Throw Forward or the Drop Asternposition, depending upon the type ofi attack'he has chosen. This switch, as has been-described, merely selects one of twotime intervals (14.5 seconds for Throw Forward and 19 seconds for Drop Astern for the values given in-Fig. 8) and its position in no way affects the -voperationof theinstrument prior to the instant ofiiring. The barrage is released 'oy momentarilyA closing the depth charge release switch S-H (on the Destroyer panel) which initiates the appropriate time interval. A diffuse light produced by signal lamp L-l appears on the destroyer screen when switch Seil is closed and remains lighted through-out the time interval; at the end of the interval when the charge has theoretically exploded,v this illumination is removed. The-.purpose of this illumination is to indicate the beginning and end of the interval and still not interfere with the observation of the light spot. During this time between the release and the explosion of the barrage, all destroyer motion (course dial and light spot) is stopped, but as is seen in Fig. 8, the instructor is free to maneuver the submarine controls; the movement ofthe light spot during this time is due only to the submarine motion. When the charge explodes, the destroyer is restored to full maneuverability and the problem may continue unless the instructor places the problem switch S3 in its 01T position.

General y The above description of the operationgof the invention from both the Destroyer and Submarine positions illustrates the-use of the device. It has been found to began exceedingly useful machine inV training andre-training men in proper conning procedure-where submarine attacks are being carried out. f

.fa-,erogare Because both'fthe student andA instructor are enabled to maneuver their' respective ships by means of the controls, practically every maneuver may be accurately simulated on the light screens. By this method, the student is not only trained in his understanding of the relative motion of the two vessels, but is limited (by the delay circuits) in executing the various procedures in the same degree which he will be limited in practice. It should he noted that, if desirable, a plurality of optical systems might be utilized to'provide a plurality of spots, to simulate motions of a plurality of ships. The instructor is thus enabled to judge the students reaction to the various situations which might be met in practice and to illustrate, without danger, the correct and incorrect methods of attack.

It should also be mentioned that the device may be used for training Submarine Oliicers in evasive tactics. In such case, the student occupies the Submarine position while the instructor operates the Destroyer position. Here again, actual conditions may be closely simulated in order to judge the students ability.

Having described the invention, we claim:

1. A device for portraying assumed relative motion between two objects, said device comprising; a screen, the center of which represents the position of one of said objects, means producing a first voltage representing an assumed absolute motion of one of said objects, means resolving' said first voltage into components representing the northsouth and east-west components of the absolute motion, means producing a second voltage representing an assumed absolute motion of the other of said objects, means resolving said second voltage into components representing the north-south and east-west components of the absolute motion, means obtaining a rst output equal to the difference between the north-south components oi said first and second voltages, means obtaining a second output equal to the diierence between the east-west components of said rst and second voltages, a light source positioned adjacent said screen and projecting a spot or" light thereon, rst

motor means energized by one of said outputs for moving said light source so as to cause said light spot to move along a vertical axis, and second motor means energized by the other of said outputs for moving said light source so as to cause said light spotto move along a horizontal axis, whereby the resultant motion of said light spot relative to the screen center will represent; motion of one of said objects relative to the other.

2. The combination in claim l wherein the inea-ns for resolving said first and second voltages into components comprises a center-tapped Dotentiometer, a pair of sliding contacts therefor, and cosine cams displaced 90 relative to each other, means for rotating said cams as a unit, and a cam follower for each cam operatively connected to said sliding contacts.

The combination in claim 1 wherein said motor means are constituted by watthour meters, the current coils of which are supplied with a constant current, and the voltage coils of which are connected respectively to said difference voltage outputs.

e. A device for portraying assumed relative motion between two objects, said device comprising; a screen, the center of which represents the position of one of said objects, means producing a rst voltage representing an assumed absolute motion of one of said objects, means resolving said first voltage into components reprosen-ting 'the' north-south-and Eeast-westcomponente Aofv the `'absolutemotion, meansr for producing a second voltage representing an assumed absolute motion of the other of'said objects, meansfresolving said second voltage into components representing thenorth-south and eastwest componentsof the absolute motion, means obtaining a rst output equal to the diierence between the north-south components of said nrst and second voltages, means-obtaining a second output equal to ,ther difference between the eastwest components of said first and second voltages, a frame,- amirror pivotally supported by said'frame, first `rnotormeans energized by one of said outputs for rotating said mirror on an axis throughits support pivots, second motor means energized by the otherl of-said outputs-for rotating said frame on an axis normal tothe axis through the mirror support pivots, and a light source associated with said mirror for projecting a spot of light on said screen whereby motion of said light spot relative to the screen center will represent motion of one of said objects relative to the other.

5. A device for portraying assumed relative motion between two objects, said device comprising; a housing, a screen at each end of the housing, the center of one screen representing the position of one moving object and the center of the other screen representing the position of the second moving object, means producing a iirst voltage representing an assumed absolute motion of one of said objects, means resolving said first voltage into components representing the north-south and east-west components of the absolute motion, means producing a second voltage representing an assumed absolute motion oi the other of said objects, means resolving said second voltage into components representing the north-south and east-west components of the absolute motion, means obtaining a first output equal to the difference between the north-south components of said rst and second voltages, means obtaining a second output equal to the difference between the east-west components of said iirst and second voltages, a yoke disposed intermediate said screens, a mirror pivotally supported on each arm of said yoke, first motor means energized 'by one of said outputs for rotating said mirrors in opposite directions about their pivotal supports, second motor means energized by the other of said outputs for rotating said yoke on an axis normal to the axis through the pivotal supports for said mirrors, and a light source associated with each of said mirrors to project a spot of light onto each of said screens whereby motion of each spot of light on its associated screen relative to the screen center will represent motion of each of said objects relative to the other.

6. In an attack training machine of the class described, a chart having a central point simulating the position of an imaginary searching craft and having radiating and concentric sets of lines for bearings and ranges, control devices adiacent said chart for providing assumed courses and speeds for said searching craft, apparatus connected to said devices and operable to integrate course and speed values into new positions for said craft, a similar second chart concealed from the operator of said control devices and having a set of bearing lines, means included in said apparatus for indicating said new positions on said second chart,'and mechanism providing and moving a point over the rst chart within-the view ofsaid operatorto afford a simulated imaginary second craft sought for purposes of attack bythe searchingcraft.

'7. In the machine of claim 6, said mechanism including a source of light behind the iirst chart and projected thereonto to provide said moving point for attack, and means for intermittently removing the point of lightfrom said chart for short time periods.

8. In the machine of claim 6, there being further control devices for the operator to simulate change of rudder of the attacking craft and to simulate release of an explosive charge.

9. In the machine of claim 6, said mechanism being similar to said apparatus, and there being control elements operable by the operator of the second imaginary craft to actuate said indicating means.

ReferencesrCi/ted inthele of4 this patent UNITED STATES' PATENTS Number 5 1,766,355 1,806,350 1,939,706 2,131,952 2,224,182 10 2,329,612 2,402,088 2,403,542

15 Number Name Date Redman June 24, 1930 Hire May 19, 1931 Karnes Dec. 19, 1933 House Oct. 4, 1938 Crooke Dec. 10, 1940 Hill Sept. 14, i943 Ross June 11, 1946 Newell July 9, 1945 FOREIGN PATENTS Country Date Great Britain 1922 

